A device of this type is known in practice and is used, in particular, in the starch-producing industry. In the latter, wheat, which contains starch, bran and vital proteins (referred to as "gluten"), is split into said three main components. The gluten is used, inter alia, in bakeries to make bread less compact. After the coarse splitting of the wheat, the gluten is still "contaminated" with residual starch. In the washing device, the gluten contaminated with residues of starch is rinsed with water at high pressure, as a result of which the starch is removed from the gluten. This involves drum screens which rotate in continuous operation and of which the length may be 6 metres and more.
In view of the acid environment prevailing inside the drum, the shafts, which are generally hollow, of said drum screens have hitherto been made of corrosion-resistant stainless steel, while the spoke-type elements supporting the circumferential wall of the drum screens have at the same time simply been welded onto the hollow shaft.
The shaft, which rotates at a rotational speed of approximately 10-20 rev/min, is exposed during operation to heavy impact loads due to the heavy masses of material which move upwards along the one side of the drum and drop down from the circumferential wall of the drum screen on reaching the top.
Under the influence of said heavy loads, fracture frequently occurs in practice and indeed, at the position of the welded joints in particular.
Although the use of larger shaft diameters and greater wall thicknesses for the hollow shaft reduces the risk of fracture, it does not eliminate it and, in addition, means an appreciable cost factor.
A solution tested by the Applicant consisted in sliding onto the stainless-steel hollow shaft bushes to which the spoke-type elements were welded and which were secured by means of bolts passing transversely through the hollow shaft. Although this measure meant an improvement with respect to the solutions in which larger shaft diameters and greater wall thicknesses were used, it is nevertheless still not effective enough to prevent rupture of the shaft.
The object of the invention is therefore to provide a gluten washing device which is more safe in operation and requires less maintenance, and the object is, in particular, to provide a more effective and, in addition, cheap solution to the abovementioned problems, as a result of which rupture of the shaft during continuous operation is prevented or the risk of rupture is reduced to a minimum.